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bsee
Senior Member
Username: bsee

Post Number: 2675
Registered: 3-2004
Posted on Wednesday, January 22, 2014 - 7:13 am:   Edit Post

So, I have been enjoying getting used to the 2000 Excel fiver I picked up a couple weeks ago. I took it to a gig on Saturday night and I couldn't use it. As soon as I plugged it in, I got an awful hum. The other bass I had with me was a Zon Sonus with single-coil Bartolinis and I had no issue with it as long as I had both pickups on even. If I pushed the pan one way or the other, I got the same hum. I was surprised to get this from an Excel since I thought the pickup was hum-cancelling. I'm wondering if there might be something off with the electronics, or if something else was going on.

This is the same rig I played the Excel through at a rehearsal without an issue. I have also been playing it in the living room through a Baby Blue II and never noticed anything out of the ordinary, though the amp is a bit noisier as it could use a bit of tech love. At least, I didn't notice anything unusual about the noise floor until I looked for it after the gig experience.

The only things that are different that I know of are:
1. The power circuits themselves.
2. I forgot my surge protector for the gig, so it was plugged straight into the wall.
3. The noise sources in the room. Obviously, there's going to be neon and such in a barroom.

The gain is about the same as we keep the stage volume in check when we gig.

Any ideas on what the cause might be or how to combat it?

Thanks!
-bob
lembic76450
Advanced Member
Username: lembic76450

Post Number: 355
Registered: 5-2002
Posted on Wednesday, January 22, 2014 - 9:38 am:   Edit Post

Bob, is there a ferrite bead in the electronics cavity? They help with noise.

http://alembic.com/club/messages/16271/16909.html?1109872910
bsee
Senior Member
Username: bsee

Post Number: 2676
Registered: 3-2004
Posted on Wednesday, January 22, 2014 - 11:46 am:   Edit Post

I'll do a cavity search. Thanks, Kenn.
mica
Moderator
Username: mica

Post Number: 8101
Registered: 6-2000
Posted on Thursday, January 23, 2014 - 4:14 pm:   Edit Post

Is the hum directional? Can you rotate different directions and find a null? That would indicate the humcanceller is disconnected from the pickup coil and the pickup will have to be replaced.

Or does it increase with the proximity of your hand to the pickup or electronics back? That indicates the pickup may be plugged in backwards. If the friction lock looks right, remove the housing and reverse it (instructions in FAQ). If the friction lock isn't aligned to lock, just plug it in correctly.
bsee
Senior Member
Username: bsee

Post Number: 2677
Registered: 3-2004
Posted on Thursday, January 23, 2014 - 9:20 pm:   Edit Post

There is a ferrite bead on the wire. I'm iffy on the construction in there, though, because there's nothing to restrain it and the bead is free to flop around. It has enough weight to it that it could bang into the boards attached to the tone controls. The board attached to the treble control has a little bit of wobble to it when touched - not sure if maybe the bead knocked it loose or it is meant to be that way. In any case, is there any reason why there shouldn't be a foam wrap on it to provide a little protection?

As far as I can tell, the hum doesn't react to hand proximity, but it might be directional. I will have to get the full rig set up to confirm, because it just isn't that pronounced in the living room with the Baby Blue to say for sure.

It may be early next week before I know for sure.

Thanks!
-bob
mica
Moderator
Username: mica

Post Number: 8103
Registered: 6-2000
Posted on Friday, January 24, 2014 - 5:09 am:   Edit Post

Is the wobble from the board to pot connection or from the bushing of the pot connection to the top wood? The cells of the wood do compress over time under the pressure of the nut, so you may just need to tighten. I'd check all the nuts, including the output jack. Heck, I check the strap pins or locks as well,

There usually is a piece of foam on the ferrite bead, so you should replace that. The adhesive can fail after enough years go by. It's not really for hum rejection, it's for RF.

Let me know if you can find a null. What is strange is that it should be acting like a single coil pickup anywhere if the humcancelling coil became disconnected.
bsee
Senior Member
Username: bsee

Post Number: 2678
Registered: 3-2004
Posted on Friday, January 24, 2014 - 7:39 am:   Edit Post

The wobble is the board vs. the pot. The pots are all solidly connected to the top. It's got maybe a 16th to an 8th inch of play if you manipulate it from the trim pot. The whole board can wiggle, and only in the one plane where you'd expect it to be possible. In any case, I'll look for some foam I can use.

Is there anything that could be going on with power input that could bring about the hum? That was really the only thing different at the gig. I tried to see if it was directional there and it didn't seem to be.

Thanks
-bob
bsee
Senior Member
Username: bsee

Post Number: 2679
Registered: 3-2004
Posted on Sunday, January 26, 2014 - 3:05 pm:   Edit Post

Looks like the hum is very directional. In the basement with the full rig today, it was prevalent with the pickup facing the amp and gone with it facing away. Looks like I will need to be emailing Mica about what it takes to get a replacement pickup. I may take the opportunity to investigate a replacement for my custom bass and a couple other minor issues while I'm at it....

Thanks all!
-bob
mica
Moderator
Username: mica

Post Number: 8114
Registered: 6-2000
Posted on Wednesday, January 29, 2014 - 4:44 pm:   Edit Post

There should be no pot/board wobble at all. The terminals are soldered and there are 2 stabilizing pins that come off the back plate of the pot. Can you see if there are missing solder joints? (!)
bsee
Senior Member
Username: bsee

Post Number: 2683
Registered: 3-2004
Posted on Wednesday, January 29, 2014 - 5:51 pm:   Edit Post

First,Mica, thanks for the cure little package of screws and foam pieces!

I will have to take the pot out to see that.there isn't much extra space there and that board with the trim pot is fairly large. I will take a look when I return home, and see if I can maybe take pics or a short video of the motion.

I should point out as well that the hum is at a fairly high frequency. It's been a while since I experienced single-coil hum, and I don't recall it what frequency it represents with.

Thanks for your continued support!

-Bob
mica
Moderator
Username: mica

Post Number: 8116
Registered: 6-2000
Posted on Wednesday, January 29, 2014 - 6:31 pm:   Edit Post

Hum is low frequency, like 60Hz, 120Hz, etc. If it's high frequency, then we are dealing with something else altogether. Does the character of the noise (that's what we'll call it if it's high frequency) change when you change the treble or bass controls?

Glad you got the package!
bsee
Senior Member
Username: bsee

Post Number: 2685
Registered: 3-2004
Posted on Thursday, February 06, 2014 - 10:07 pm:   Edit Post

Now I'm confused.

At rehearsal, I went about checking details. I found that I only had higher frequency directional noise when within about two feet of the amp head. This noise had the same character as what I had at the gig that started this mess. In that case, though, it was non-directional and distance didn't matter.

I don't recall any change as I rotated controls, but I don't think I was as diligent as I should have been in testing this aspect of the issue. I will do better this weekend.

Is there any possible explanation in the environment, the cabling, or the power feed that could explain the problems at the gig? The fact that my other bass made a very similar noise in that situation when on one single-coil pickup really makes me wonder if it was related to the environment. My other question is whether a potential loose connection in the preamp related to the moving circuit board could have been in a bad connection position at the gig, but was okay at rehearsal? This is a long shot since the issue occurred with either bass at the gig. My guitarist was playing a strat and had no issues, so I am leaning toward a power input issue if that sort of thing could explain it. Maybe a shared ground with some kind of lighting item?

I want to gig this bass, but I need to understand the what went wrong so I can trust it. We've got a Valentines Day show at a new venue and I'll bring it with me for at least a sound check, but I'll be prepared to put it right back down if there's an issue.

Thanks!
-bob
keith_h
Senior Member
Username: keith_h

Post Number: 1958
Registered: 2-2005
Posted on Friday, February 07, 2014 - 5:08 am:   Edit Post

If you were near any neon lighting, computers/terminals or motors such as blenders there could be enough interference to appear non-directional. Another area to consider is stage lighting.

Keith
jazzyvee
Senior Member
Username: jazzyvee

Post Number: 3853
Registered: 6-2002
Posted on Friday, February 07, 2014 - 6:16 am:   Edit Post

This may or may not be of any help but its useful to know where the sources of noise may be. When I bought my Series bass guitar a few years back I was plagued with a sizzling noise from it and could not work out what it was.

It never happened on my other guitars but when ever I used the series I guitar I would get this sizzle. Eventually i took the DS-5 to get checked out in case of problem with that and they put in more smoothing capacitors but it made no difference. Eventually I found the cause to be the powerline ethernet over mains adapters I was using to transmit the internet signals round the house. When I turned them off there was no noise problem. These days I have a filter and surge protector mains plug board and recently upgraded the powerline adaptors and even without the mains filter leads they are significantly quieter but not completely silent.

http://www.pcworld.co.uk/gbuk/powerline-home-networking/xx_7090_70097_xx_xx/xx-criteria.html

Jazzyvee
mica
Moderator
Username: mica

Post Number: 8122
Registered: 6-2000
Posted on Friday, February 07, 2014 - 1:22 pm:   Edit Post

It seems like you should pull the wiggler and make sure there are sound solder connections there. Without overnighting it's not practical to send the guts here before your Feb 14th gig, but do remember there is no charge to test any Alembic product.

Also, 2 feet away? Is it me or isn't that sort of close? Is it possible to stay three feet away (which still seems close to me)?
bsee
Senior Member
Username: bsee

Post Number: 2686
Registered: 3-2004
Posted on Friday, February 07, 2014 - 9:40 pm:   Edit Post

The proximity was just about a hum test, not a legitimate playing position. Though, you know what it's like to be a bass player, the lead guitar and singer take 90% of the stage that doesn't have drums on it and we usually get about six square feet of floor space. The rehearsal space hasn't given me any noise problems at all, further evidence that it was an environmental thing when I had noise.

The night I had problems, I had about 8' of space from my rig to my mic. It didn't matter where I was in that space, or even another few feet off to the side. I got the same higher frequency noise either with the Excel or with the Zon if the pickup blend was all the way off center. If I centered the blend, it was quiet.

Like I said, the one big difference is that I didn't have my good power strip with me that night. I know there was an LED light hooked into the same circuit, and possibly a small powered PA monitor. I'll look into the wobble when I get a chance and I won't forget the power strip, so we'll see what I get. I get set up early enough to run a check and carry a backup, so it's never the end of the world if one thing goes wrong.

I am leaning toward the power feed being the issue, but I was surprised that the Excel acted similarly to the Zon in one-single-coil-pickup mode. I would have expected it to mirror the Zon in both-pickups-full-on mode.

Also, we've got 2-3 gigs a month for the foreseeable future, so there will never be a convenient time to ship parts across the country. Fortunately, I'm in the too-many-basses club, so time can be made if it seems the right thing to do.

We won't be back in that problem room until June, so I will monitor things in the meantime and if it's still a problem then with the good power strip in place, I'll think about pulling the guts and sending them west.

-bob
bsee
Senior Member
Username: bsee

Post Number: 2689
Registered: 3-2004
Posted on Thursday, February 20, 2014 - 12:21 pm:   Edit Post

Still having problems at gigs, but it's fine at rehearsals. No idea what's going on. I am going to put a brand new battery in there and try it on Friday. If it's still not good, I guess I'm going to have to pull everything and ship it.

Just proof that not every low price is necessarily a great deal. I'm sure this was a great deal and that is an over-reaction, but frustration can do that to you. It's more about not being able to figure out what's wrong than it is about the problem itself.

-bob
sonicus
Senior Member
Username: sonicus

Post Number: 3233
Registered: 5-2009
Posted on Thursday, February 20, 2014 - 4:34 pm:   Edit Post

It might not be the instrument at all . I have measured EMF interference etc... in a variety of places with a Gauss meter . I would check the power plugs in the suspected area first for hot / neutral/ ground correctness as a first step . Next if you can get a hold of a Gauss meter
or equivalent equipment to measure for any magnetic fields or various RF / EMF noise would be my next step. The fact is that you are not experiencing this noise problem at your rehearsal !
Therefore ; perhaps this is a localized environmental issue ____

Gauss meter http://www.lessemf.com/gauss.html
sonicus
Senior Member
Username: sonicus

Post Number: 3234
Registered: 5-2009
Posted on Thursday, February 20, 2014 - 4:50 pm:   Edit Post

More Gauss meters ! http://www.google.com/search?client=safari&rls=en&q=gauss+emf+meter&ie=UTF-8&oe=UTF-8#q=gauss+emf+meter&rls=en&tbm=shop
bsee
Senior Member
Username: bsee

Post Number: 2690
Registered: 3-2004
Posted on Friday, February 21, 2014 - 12:09 pm:   Edit Post

There's no doubt that there's more to this than just the instrument since there are locations where I have no difficulty. On the other hand, at locations where there is an issue, the issue only exists with this bass. Guitar player on single coils has no unusual noise and my other bass doesn't either. The one exception is that my other bass in a mode with just one single coil active does get some noise. If it's related to something picked up in a single coil environment, then that's a problem that shouldn't happen on a single-pickup Alembic in good working order.

The place I am playing tonight is not a real stage setup with lights and such, just a corner of a bar room. It will be the simplest gig environment yet in terms of noise sources. Even if it works well tonight, though, that will just be a data point. If I can't use the bass in 2/3 of the places I gig, then I need to do something about it.

-bob

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